Native S-60 and its deacetylated forms are described in U.S. Pat. Nos. 4,326,052 and 4,326,053. S-60, native, clarified, and non-clarified, form thermoreversible gels upon heating and subsequent cooling. Deacetylated S-60 is also characterized in that it exhibits reduced solubility in salt solutions. The heating requirement is undesirable in certain systems; i.e., it would be preferable in systems where heat would adversely affect certain components to be able to produce an S-60 gel at ambient temperature.